1. Field of the Invention
The present invention relates to an optical lens having an optical function portion and a flange portion, a lens unit, an imaging module, an electronic apparatus, an injection molding mold, and an injection molding method.
2. Description of the Related Art
Mobile-type electronic apparatuses such as a mobile phone having an imaging function are equipped with a small and thin imaging module. The imaging module has a structure where a lens unit and an imaging element unit are incorporated. The lens unit has a built-in imaging lens. The imaging element unit has a built-in imaging element such as a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor.
Most of the optical lenses built into lens units are formed through injection molding using resin.
For example, JP2010-014983A discloses a method of molding a resin lens, which is used as a pickup lens for optical discs, by using an injection molding mold. The resin lens is molded together with a sprue portion which is formed of a sprue, a runner section which is formed of a runner, and a gate portion which is formed of a gate.
US2013/0148208A discloses a method of molding a plastic optical lens having a sprue gate surface by using an injection molding mold. According to the method, in order to avoid voids in the optical effective diameter region and linear defects called weld lines occurring, a protrusion portion of an optical lens is formed due to a channel of an inlet disposed between an optical effective diameter region and the sprue gate surface, and molten resin is prompted to rapidly flow into the optical effective diameter region at the time of molding.